Oh man, this is like WWIII (potentially). As I said, I retired in 1994 so I have not been actively following these issues on a daily basis. But, these folks
http://www.firearmstactical.com/wound.htm
have some pretty impressive crdentials and list lots of data and articles (there are many others).
This "business" is full of "myths" and "false prophets". And, these guys seem to be interested only in facts and real scientific data (at least as scientific as it can get). There will always be anecdotal anomolies, always... ANd, at either end of the spectrum. The deadly... .22LR (and it really is lethal many times, but usually as a result of the infections they cause)... And, then the perp with 10 hits from a .45 that drives away and removes the bullets alone in the motel room using vodka and a pocket knife...
Here goes, an additonal IMHO statement to expand on my previous one. First, not to belabor the point, but first as a firearms instructor, then the department Rangemaster and a Supervisory Officer of the county's Tactical Team, it was my business to know as much about this matter as possible. Second, I have been on both ends of the gunfight, with the USMC in Vietnam and then as a police officer. None of that was "fun", but it was (for lack of a better term) "educational". I learned a few things along the way... I like the .223 for hunting... for combat I'll take a .308 or better any day... They just "work better"! And, in handguns, I like the .45ACP, then the .357, then the .40 and then the .38SPL and the 9mm is last... All based on "data" and experience...
The .45ACP works and works about as well as any handgun round is going to work... There are bigger and "badder" rounds but they aren't practical for a broad discussion... I will however admit that a .50 in A Desert Eagle will do just fine... And, the old .44 AutoMag will work also, and it too, quite well.... but not in the hands of the "usual" folks that need a defensive handgun... civilian or police.
The .40 is "almost" as good as a .45ACP... just ask around and that is the usual answer... Werll why get the "almost", when you can have the "good as" round. And, the .40 (and moreso, the 10mm... I love my Colt Delta) are asking way too much from the round... high pressures are not the friend of functionality, short or long term.
The .357 works almost as well as the .40 and has its own great attributes because of the platform... revolovers are just a good platform and tool. The reloading should not be an issue... if you need more than the six (or 7) rounds available you should have had time to retreat and get a long gun...
The 9mm suffers from a lot of poor real world performance reports. Usually, because someone is asking it to do a job it is not engineered to do... It is .75 inches long and the .38SPL is 1.115 inches long. They have the same diameter so go figure... How is the little brother going to outdo its taller relative? The engineers talk about velocity and lighter bullets...
The .38SPL in new modern revolvers can handle vastly higher pressures than most factory ammo... thus the +P and +P+ loads... Just don't use them in the older little Chief's Specials... But, in a modern heavy barrel Model 10... Virtually .3576 velocity with heavier bullets.
Now, I have already spouted off about hollow points in handguns... So, I will just ask this question... You have four major variables... Diameter... Velocity... Weight... and Bullet shape/construction... Bigger/More is better and since the "energy" fascination has been long ago debunked... Momentum and transferring that momentum is what really counts in handgun ammo... Do some math...
And, more importantly, listen to the combined wisdom of the "been there and done that" crowd. The anecdotal information, time and time again reports that the bigger heavier bullets are more effective than lighter smaller bullets.
For whatever reason, I guess mostly psychological, a "pass through" shot does not "end" the argument as well as a bulet that expends all its momentum in the target.
For my money, time and safety, I'll always take a caliber that starts with a "4" if I can, and if I can't and I get to pick one that starts with a "3", I'll go for the heavier bullet at some reasonably jacked up velocity that will not result in a pass through and will expend its energy in the target... And, lastly, recognizing that "expansion" is unreliable at handgun velocities, I will not try to rely on bullets that need to expand to be effective...
All of that said, I end up with wanting a .45ACP in a single stack 1911 (no DA for me)... carried cocked and locked. Or, a .357 or "hot" .38SPL in a good revolver.